Dendritic nanoporous nickel oxides for a supercapacitor prepared by a galvanic displacement reaction with chlorine ions as an accelerator

Dendritic nanoporous nickel oxide and tube-like nickel–tin oxide electrodes were prepared by a galvanic displacement reaction in an aqueous electrolyte containing chlorine ions which dramatically accelerated the reaction. The nanoporous nickel oxide showed a capacitance of 1242 F g−1, 97.4% of which was retained even after 5000 charge–discharge cycles.